The present invention relates to a distraction apparatus for orthodontic, orthognathic and oral/maxillofacial surgery applications on the mandible which is used for distraction osteogenesis of a dentate anterior bone segment.
The present distraction apparatus has its application in orthodontics, orthognathic surgery and general oral and maxillofacial surgery. It is its purpose to provide the surgeon with a tool to distract bony segments, e.g. in the area of the anterior mandible. In particular, such an apparatus should enable the surgeon to achieve a more prominent chin or to translate an anterior bone segment including the integrated teeth and to change its dental axis, if required.
In oral/maxillofacial surgery there is often the need to precisely move a bony segment gradually, to rotate it into a different position or to combine both movements. Thereby, the movement is achieved over several days after the osteotomy in the sense of a so-called callus distraction.
One application is genioplasty, where the anterior lower edge of the mandible is detached and reattached in a more advanced position by means of osteosynthesis screws; the goal of this procedure is to increase the prominence of the chin, e.g. in the case of a too posterior position, in order to provide the patient with a more aesthetic facial profile. Typically, this movement is done in one step which may result in discontinuities in the bony profile at the osteotomy site and therefore also the soft tissue profile of the lower mandibular edge. Furthermore, the soft-tissue in the area of the chin are heavily stretched and strained in a one-step translation.
In another application there is the need, to loosen an anterior segment of the alveolar ridge with the included dentition and to move this segment more to the front and/or to rotate it, e.g. to gain more space for the teeth in the case of an anterior dental crowding, or to provide some more length to a mandible which is slightly to short relative to the maxilla, in order to achieve an improved occlusion. Such movements were also done in one step, in the past. This has the disadvantage that it limits the achievable movement since sufficient overlapping between the osteotomy surfaces has to be retained. Furthermore also here the soft tissues are heavily stretched which can result in dehiscence of the mucosa in the area of the osteotomy.